The rap start was really working even though Sir Paul McCartney could not tell.

(AllHipHop News) Sir Paul Mccartney had no idea Kanye West was coming up with rhymes during a get-together in 2014, because he spent the whole time staring at photos of his wife Kim Kardashian.

The Beatles and Wings icon agreed to collaborate with Kanye four years ago, and headed out to Los Angeles for a relaxed brainstorming session to see what they could come up with.

However, McCartney admits he didn't think much of the meeting at first, because the rapper didn't appear to be showing any interest in buckling down and getting to work.

"With Kanye, I learnt a lot," McCartney told DIY, as he outlined the songwriting process he developed early on.

"We had a method in our early days of The Beatles and with Wings that I used all the way through for writing songs," he said. "I would sit down with a guitar or at a piano and make it up and complete it. Then that's it, you've done your song, and then you're ready to roll and go in the studio."

However, he quickly discovered there was even less structure to the way Kanye works.

"With him, it was much more made up as we went along - so much so that I didn't even realize that I was making songs," he confessed.

"We had two or three afternoons where we just hung out together in a Beverly Hills hotel in the bungalows out the back, and he had his engineer and was set up with a couple of microphones in case anything happened. I was tootling around on guitar, and Kanye spent a lot of time just looking at pictures of Kim on his computer.

"I'm thinking, 'Are we ever gonna get around to writing?!' But it turns out he was writing. That's his muse. He was listening to this riff I was doing and obviously he knew in his mind that he could use that."

The track ended up becoming their 2015 hit "FourFiveSeconds," which featured another big star McCartney was already a fan of.

He continued, "(Kanye) took it, sped it up and then somehow he got Rihanna to sing on it. She's a big favorite of mine anyway, so that just came without me lifting a finger."